One of the greatest Seattle days in the history of Catalina, Arizona

Yesterday, that is.  It felt like I never left.  Only 49 F here; was 55 F in Seattle yesterday.

But the main thing that made it seem “so Seattle” was the persistent low Stratocumulus overcast, almost no sun whatsoever, and a little rain.  We picked up another 0.03 inches in a couple of morning episodes of R– (an old weather texting1 shorthand for “very light rain”) to bring the storm total here to 0.55 inches.  Of course, the best part of that overcast was that it allowed the ground to be damp for another day, helping the spring grasses and wildflowers by keeping the soil moisture in the soil and not flying away under a hot sun.  The worst part of the overcast that lasted almost all day, was that Mr. Cloud Maven person had the day completely wrong–thought it would break open in the afternoon to “partly cloudy” and so he was as gloomy as the sky.  You see, as a weather forecaster, you can’t even really enjoy a nice day if you didn’t predict it.  Had some sad 75 F days in Seattle when I only predicted 69 F;  everybody having summer fun but me.

Enough nostalgia, here are the clouds, even if you have no interest in seeing such boring clouds again:

6:56 AM.  Interesting little punctuated lenticular.  Mr. CMP has finsihed his blog and thinks the sky will break open in the afternoon.  Hah!
6:56 AM. Interesting little punctuated lenticular.  Mr. “CMP” has just finished  his long blog and thinks the sky will break open in the afternoon. Hah!

 

8:00 AM.  Stratocumulus tops Samaniego Ridge--with the turrets, you might lean toward adding the descriptor, "castellanus."  Note blue sky here, if you didn't see any at all yesterday.
8:00 AM. Stratocumulus tops Samaniego Ridge–with the turrets, you might lean toward adding the descriptor, “castellanus.” Note blue sky here, if you didn’t see any at all yesterday.  No precip evident.
8:02 AM.  Looking north toward S-Brooke.  Fine shafts of precip emit from Stratocumulus clouds indicating those regions in the cloud where there was more liquid water at one time, where these clouds are humped up like those Sc clouds on Samaniego Ridge.  But, was the precip due to ice or the colliding drops process?  I wasn't sure at this point.  You see, after a storm, the clouds can be real clean, almost oceanic-like meaning they have LOW droplet concentrations, and when the droplet concentrations are low, the drops are usually larger and can get to sizes where they stick together when they collide (think 30-40 micron diameters).  You probably have a clue about that size, but it sounds great if you see this and tell a neighbor that, "those clouds might have drops larger than 30-40 micron near cloud tops."  Instant expert!
8:02 AM. Looking north toward S-Brooke. Fine shafts of precip emit from Stratocumulus clouds indicating those regions in the cloud where there was more liquid water at one time, that is, where these clouds are humped up like those Sc clouds on Samaniego Ridge in the prior photo (the precip from those clouds may have been out of sight).                                               But, was the precip shown here due to ice or the colliding drops process? I wasn’t sure at this point. You see, after a storm, the clouds can be real clean, almost oceanic-like meaning they have LOW droplet concentrations, and when the droplet concentrations are low, the drops are usually larger and can get to sizes where they can stick together when they collide (think 30-40 micron droplet diameters). You probably don’t have a clue about those sizes, but it sounds great if you see rain like this and tell a neighbor that, “those clouds might have drops larger than 30-40 microns in diameter near cloud tops.”  Instant neighborhood expert!

 

8:06 AM.  Then the clouds to the west of Oro Valley and Catalina began to produce fine precipitation, definitely looking like a true drizzle event (caused by colliding drop rain formation process), at least to me at this point.  This is a rare event when very light rain or true misty drizzle (tiny drops, close together) occurs in Arizona.  Usually our clouds have too many droplets from natural and anthropogenic sources and the cloud droplets stay too small to collide and stick together, instead bumping around like marbles with all the surface tension they got.
8:06 AM. Then the clouds to the west of Oro Valley and Catalina began to produce fine precipitation and advance on Catalina.  How nice.   Definitely was looking like a true drizzle event (caused by colliding drop rain formation process), at least to me at this point. That process is a rare event in AZ when very light rain or true misty drizzle (tiny drops, close together) forms like that. Usually our clouds have too many droplets from natural and anthropogenic sources and the cloud droplets stay too small to collide and stick together, instead bumping around like marbles with all the surface tension they got.  And then because they’re all tiny, they don’t have much impact when they hit, there’s not a lot of velocity difference like there would be in a cloud with a broad droplet spectrum, the kind of spectrum we see in “clean” clouds where drops bigger than 30 microns are a plenty.   Note trails of precip coming down in center.  BTW, to go way off topic, to distract from how bad my forecast was, in “hygroscopic” seeding, particles like salt are introduced at cloud base to encourage the formation of rain through this process in polluted Cumulus clouds.  Worked in Saudi, based out of Riyadh, winter of 2006-07, flying in a Lear jet, helping to select Cu for random seeding using that methodology2.  Our office at the government met building, I recall, was cleaned  by the “Bin Laden” group.   Hmmmm.  Maybe its a common name there, to go even farther off topic.
10:09 AM.  So Seattle! (Have to make up for that last bloated caption.)
10:09 AM. So Seattle! (Have to make up for that last bloated caption.)
4:49 PM.  And that's your entire day.
4:49 PM. And that’s your entire day.
6:27 PM.  Sunset tried to do something.  But, like the day, it was like that sugar icing on a stale cinnamon roll, just didn't quite make it, though cinnamon rolls are quite good as a rule.
6:27 PM. Sunset tried to do something. But, like the day, it was like that sugar icing on a stale dried out cinnamon roll, just didn’t quite make it, though cinnamon rolls are quite good as a rule.

Today’s clouds

Some residual small Cumulus, maybe clumping into a larger group this morning for a bit, which you would then refer to as Stratocumulus. Should gradually diminish in size and coverage until almost completely clear in the afternoon.  Expect a north wind in the afternoon, too.

The weather ahead

There isn’t any, well, not right away, but WAY ahead….

Chances for rain begin to pick up after the 19th as we enter the “zone of curl”, “cyclonic curls” in the upper atmosphere with a lot of “vorticity” in them again, with temperatures falling back to normal values.   Pretty tough to have warm weather for long at this time of year in AZ.   You see, its troughs like to “nest in the West” in March, April, and May, even when they’re not strong and far enough south to bring rain, maybe only wind. Its a climo thing, and it causes many areas of the West to see an increase in precipitation in March from February, and also halts the rapid rise in spring temperatures (especially in Seattle, hahahaha, sort of).

This because the global circulation pattern, responding to the climb of the sun in the sky and warming continents in the northern hemisphere, those forces acting on the position of the jet stream, and weakening it here in the NH (northern hemisphere), is changing the jet stream pattern so that storms begin to move southeastward from the north Pacific across the Pac NW into the Great Basin area in the spring, bringing cold north Pacific air into the West. There was a great report about this phenomenon by old man Bjerknes out of UCLA with his Ph. D. grad student, Chuck Pyke, back in the mid-1960s.  Pyke was a UCLA sports nut, BTW, to add some color to this account.

We won’t see that “trough in the  West” pattern for awhile here in our “oasis of warmth” now about to begin, but count on it returning, as it appears to do late in the model runs from last night.  Climo is forcing it.

The End, except for footnotes.

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1Yeah, that’s right. Weathermen, as we would say it then,  were way ahead of their time,  “texting” each other long before kids thought of “texting.”   You might write a weather friend, if you could find one:  “We had a TSTM to the S with FQTLTGCCCG ALQDS last night for a few H. MVD N.”    PIREPS, SIGMETS, too, were all “texted” and texted by teletype! Tell your kids.

2Was under the aegis of Research Applications Program (RAP) at the National Center for Atmospheric Research (NCAR) in Boulder, CO.  Money was good…though not nearly as much as you would make as a TEEVEE weather presenter (hahaha).  I was a post retiree guest scientist for RAP NCAR.  Clouds could be real bumpy there in Saudi, thought I was gonna die once as bottom dropped out of the Lear going into Cumulonimbus at night that one time.  Pilot liked to cut it close between the hail shafts and the rising parts of the Cu with little or no precip, using his aircraft radar.  But sometimes, it was a little too close…and we got into the shear zone between a strong updraft and the downdraft.